Normality Calculator
When One Mole Doesn't Equal One Reactive Unit
Sulfuric acid can donate two protons per molecule; sodium hydroxide donates only one hydroxide. Treating both as equally "concentrated" at the same molarity would be misleading for an acid-base reaction, since sulfuric acid reacts twice as hard per mole. Normality corrects for this by counting reactive equivalents rather than molecules, which is why it's still the preferred unit in titration and redox chemistry.
The Formula
The n-factor is the number of reactive units each formula unit provides — equivalents of H+ or OH− for acid-base chemistry, or equivalents of electrons transferred for redox chemistry.
Where This Calculation Matters
- Acid-base titrations — normality lets a 1:1 volume ratio directly indicate a stoichiometric match, regardless of how many protons each species donates.
- Redox titrations — normality accounts for the number of electrons transferred per formula unit, which varies by reaction.
- Water treatment and hardness testing — normality is the traditional unit for reporting equivalents of hardness-causing ions.
- Comparing reactive capacity — two solutions at equal normality neutralize the same amount of a given titrant, even if their molarities differ.
Normality for Common Acids and Bases at 1 mol/L
| Substance | n-factor | Normality (at 1 mol/L) |
|---|---|---|
| HCl | 1 (one H+) | 1 N |
| H2SO4 | 2 (two H+) | 2 N |
| NaOH | 1 (one OH-) | 1 N |
| Ca(OH)2 | 2 (two OH-) | 2 N |
| H3PO4 | 3 (three H+) | 3 N |
A 1 mol/L solution of H2SO4 has the same acid-neutralizing capacity as a 2 mol/L solution of HCl, because normality (2 N in both cases) is what actually predicts reactive equivalents.
How to Use This Calculator
- Enter the Molarity (mol/L) of the solution.
- Enter the n-factor (equivalents per mole) for the specific acid, base, or redox species involved.
- Select Calculate to get the normality in equivalents per liter (N).
Related Calculations
Need the equivalent weight for weighing out a normal solution? Use the Equivalent Weight Calculator. For the underlying molarity from a mass and volume, see the Molarity Calculator.